JP5954493B2 - Continuous heating furnace - Google Patents

Description

The present invention relates to a continuous heating furnace that burns fuel to heat an object to be fired.
This application claims priority based on Japanese Patent Application No. 2013-75985 for which it applied to Japan on April 1, 2013, and uses the content here.

Conventionally, a continuous heating furnace in which a radiant body is heated by combustion heat obtained by burning a fuel gas, and a fired object such as industrial material or food to be conveyed is radiated from a radiant surface of the radiant body has been widely used. Yes. For example, in a continuous heating furnace that fires rice crackers, a plurality of heating furnaces are arranged in series in the conveying direction, and the rice crackers sequentially pass through the inside and outside of the heating furnace, thereby firing the rice crackers. And cooling are repeated alternately. Thus, the surface of the rice cracker is transferred to the inside without being burned too much (for example, Patent Document 1).

Moreover, the technique of the continuous heating furnace which provided the heating area | region which arrange | positions a burner, and the cooling area | region which arrange | positions the heat exchanger tube for cooling in the furnace is disclosed (for example, patent document 2). In this technology, the exhaust gas ejected from the burner collides with the material to be fired in the furnace to heat the material to be fired, and the flow of exhaust gas from the heating region (slow cooling region) to the cooling region is suppressed by the partition wall. ing. The air before being supplied to the burner flows through the heat transfer tube, and the air flowing through the heat transfer tube is preheated by the heat of the atmosphere in the cooling region while the heat transfer tube cools the atmosphere in the cooling region.

Japanese Patent No. 4890655 Japanese National Publication No. 62-15234

In the case of the continuous heating furnace described in the above-mentioned Patent Document 1, heat loss occurs as much as the object to be fired is cooled outside the furnace. On the other hand, if it is a continuous heating furnace of patent document 2, since the heat radiated at the time of cooling is utilized for the preheating of the air supplied to a burner, thermal efficiency will increase. However, even if a partition wall is provided, the cooling region cannot be hermetically sealed so that the object to be fired can continuously pass through the cooling region. As a result, the temperature of the atmosphere in the cooling region rises due to convection from the heating region side, and it becomes difficult to sufficiently cool the object to be fired.

In view of such problems, an object of the present invention is to provide a continuous heating furnace capable of satisfying both sufficient cooling performance and high thermal efficiency when heating and cooling an object to be fired.

In order to solve the above-mentioned problems, a continuous heating furnace of the present invention includes a furnace body, a transport unit that transports the fired object in the furnace body, and a fired product that is heated by combustion and is transported by the transport unit. A first radiating surface for transferring radiant heat and having a plurality of heating units arranged in parallel in the furnace body in the conveying direction of the object to be baked, and to be baked when facing the object to be baked conveyed by the conveying part And a cooling preheating part having a gas flow path for preheating gas used for combustion in the heating part by heat from the second radiation surface receiving radiation heat from the object.

The first radiation surface and the second radiation surface may be arranged adjacent to each other in the conveyance direction of the object to be fired. Further, the first radiation surface is located between the first radiation surface and the second radiation surface in the transport direction and extends closer to the object to be fired than the first radiation surface and the second radiation surface in a direction perpendicular to the transport direction. You may further provide the shielding part which has a surface perpendicular | vertical or inclined with respect to at least one of a surface and a 2nd radiation | emission surface.

The first radiating surface and the second radiating surface are arranged adjacent to each other in the conveying direction of the object to be fired, and the adjacent first radiating surface and second radiating surface are closer to one end side of both ends in the conveying direction. However, you may incline with respect to a conveyance direction so that it may become near a conveyance part rather than the other end side.

You may further provide the adjustment part which adjusts the heat transfer amount by the radiant heat from the surface of a to-be-baked thing to the 2nd radiation surface so that the surface temperature of to-be-fired thing is maintained more than the center temperature of a to-be-fired thing.

According to the present invention, it is possible to achieve both sufficient cooling performance and high thermal efficiency when heating and cooling a workpiece.

It is the perspective view which showed the example of the external appearance of a combustion heating system. It is the perspective view which showed the cross section along the II-II line | wire of FIG. It is sectional drawing along the III (a) -III (a) line | wire of FIG. 1 for demonstrating a combustion heater. It is an enlarged view of the part enclosed with the broken line of FIG. 3A. It is a figure for demonstrating a projection part. It is a figure for demonstrating a continuous heating furnace. It is a perspective view for demonstrating arrangement | positioning of a combustion heating system and a cooling preheating part. It is sectional drawing of the cooling preheating part along the VI (b) -VI (b) line | wire of FIG. 6A. It is the functional block diagram which showed the schematic structure of the continuous heating furnace. It is a figure for demonstrating the function of an adjustment part. It is a figure for demonstrating the function of an adjustment part. It is a figure for demonstrating the modification of the continuous heating furnace which concerns on this invention. It is a figure for demonstrating the modification of the continuous heating furnace which concerns on this invention. It is a figure for demonstrating the modification of the continuous heating furnace which concerns on this invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

The continuous heating furnace of this embodiment is provided with a plurality of combustion heating systems in the furnace. First, the combustion heating system arranged in the furnace will be described, and then the overall configuration of the continuous heating furnace will be described.

(Combustion heating system 100 (heating unit))
FIG. 1 is a perspective view showing an example of the appearance of the combustion heating system 100, and FIG. 2 is a perspective view showing a cross section taken along the line II-II in FIG. The combustion heating system 100 in the present embodiment is a premixed type in which city gas or the like and air as a combustion oxidant gas are mixed before being supplied to the main body container. Alternatively, a diffusion type that performs diffusion combustion may be used.

As shown in FIGS. 1 and 2, the combustion heating system 100 includes a plurality of (in this case, two) combustion heaters 110 connected in series, and a mixed gas (hereinafter referred to as “fuel gas”) of city gas or the like and air. ”) And the fuel gas burns in each combustion heater 110 to generate heat. In the combustion heating system 100, exhaust gas generated by the combustion is recovered.

Further, a fire transfer portion 102 that communicates with a sealed space in the combustion heater 110 provided continuously is formed at a connection portion between the both combustion heaters 110. However, when used in gas, it is not always necessary to completely seal the sealed space.

In the combustion heating system 100 of the present embodiment, for example, a single flame is ignited by an ignition device such as an igniter (not shown), and the flame is spread and ignited in the combustion heater 110 continuously provided through the fire transfer unit 102. As described above, the combustion heating system 100 is provided with the two combustion heaters 110. Since both the combustion heaters 110 have the same configuration, only one of the combustion heaters 110 will be described below.

3A and 3B are explanatory diagrams for explaining the combustion heater 110. FIG. 3A is a cross-sectional view taken along line III (a) -III (a) in FIG. 1, and FIG. 3B is an enlarged view of a portion surrounded by a broken line in FIG. 3A. In FIG. 3B, the white arrow indicates the flow of fuel gas, the hatched arrow indicates the flow of exhaust gas, and the arrow filled with black indicates the movement of heat.

As shown in FIGS. 3A and 3B, the combustion heater 110 includes a heating plate 120, an arrangement plate 122, a partition plate 124, a heat insulating portion 126, a combustion chamber 128, a sealing portion 130, and a sealing portion 132. And a heat insulating material 134, a first piping part 136, a second piping part 138, an introduction part 140, and a lead-out part 142.

The heating plate 120 is a thin plate member formed of a material having high heat resistance and oxidation resistance, such as stainless steel (SUS), or a material having high thermal conductivity, such as brass. The heating plate 120 has a first radiation surface 120a. The first radiation surface 120a is formed in a substantially rectangular shape (see FIG. 1), is heated by heat generated by combustion, and transfers radiant heat to the object to be fired.

The outer wall portion 120b of the heating plate 120 is bent at the outer periphery of the first radiation surface 120a and stands up (extends in the direction perpendicular to the first radiation surface 120a and away from the first radiation surface 120a (downward in FIG. 3A)). ), Forming the side of the combustion heating system 100.

In the present embodiment, the heating plates 120 of the two combustion heaters 110 are integrally formed (see FIG. 2). The heating plate 120 forms a hole with the inner surface of the outer wall portion 120b as a side surface and the back surface 120c of the first radiation surface 120a as a bottom surface, and the components of the two combustion heaters 110 are formed in the hole. Arranged.

The arrangement plate 122 is a flat member formed of a material having high heat resistance and oxidation resistance, such as stainless steel or a material having low thermal conductivity. The arrangement plate 122 is arranged inside the outer wall portion 120b of the heating plate 120 so as to face the back surface 120c of the first radiation surface 120a of the heating plate 120 substantially in parallel.

Like the heating plate 120, the partition plate 124 is a thin plate-like member formed of a material having high heat resistance and oxidation resistance, such as stainless steel, or a material having high thermal conductivity, such as brass. The partition plate 124 is disposed on the inner side of the outer wall portion 120 b of the heating plate 120 between the back surface 120 c of the heating plate 120 and the arrangement plate 122 so as to face the arrangement plate 122 substantially in parallel.

The arrangement plate 122 and the partition plate 124 have substantially the same outer peripheries (outer shapes) of the opposing surfaces, and each has a track shape (a shape in which the two short sides of the rectangle are changed to line-symmetrical arcs (semicircles)). I am doing.

The heating plate 120, the arrangement plate 122, and the partition plate 124 may be arranged so as to be opposed to each other as long as a gap is formed therebetween. Moreover, there is no restriction | limiting in the thickness of the heating plate 120, the arrangement | positioning board 122, and the partition plate 124, You may form in unevenness not only in a flat plate.

The heat insulating portion 126 is a thin plate member formed of a material having high heat insulating properties (having heat insulating properties), for example, ceramic. The heat insulating portion 126 has an outer peripheral portion 126a and a bottom surface portion 126b.

The outer peripheral portion 126 a is located on the outer peripheral side of the partition plate 124, and extends along the outer periphery of the partition plate 124 in the facing direction of the heating plate 120 and the arrangement plate 122 (vertical direction in FIG. 3A). The bottom surface portion 126b is a portion that is bent and continuous from a portion of the outer peripheral portion 126a on the arrangement plate 122 side (lower side in FIG. 3A), and extends toward the center of the arrangement plate 122. Arranged to face each other.

The heat insulating portion 126 has a hole 126c having a bottom surface portion 126b as a bottom surface and an inner surface of the outer peripheral portion 126a as a side surface, and the outline of the hole 126c is similar to the outer shape of the arrangement plate 122 and the partition plate 124. It has a track shape. And the outer peripheral part 126a is spaced apart from the outer peripheral surface 122a of the arrangement | positioning board 122 and the outer peripheral surface 124a of the partition plate 124 via the hole 126c.

As shown in FIG. 3B, the combustion chamber 128 is located between the outer peripheral portion 126a and the outer peripheral surfaces 122a and 124a of the arrangement plate 122 and the partition plate 124, and faces the outer peripheral surfaces 122a and 124a. That is, the combustion chamber 128 is surrounded by the outer peripheral surfaces 122a and 124a, the heating plate 120, and the heat insulating portion 126, and a space located inside the outer peripheral portion 126a along the outer peripheral portion 126a (that is, a space overlapping the hole 126c). It has become.

The sealing part 130 can be configured by a thin plate-like member formed of a material having a lower heat insulating property than the heat insulating part 126, for example, stainless steel. In the present embodiment, the sealing portions 130 of the two combustion heaters 110 are integrally formed (see FIG. 2).

Further, as shown in FIG. 3B, the sealing portion 130 has a bent portion 130a extending in the surface direction of the back surface 120c (hereinafter simply referred to as “surface direction”) at the contact portion of the first radiation surface 120a with the back surface 120c. The bent portion 130a is joined to the back surface 120c of the heating plate 120 by welding or brazing. Therefore, gas leakage to the heat insulation part 126 side of the combustion chamber 128 is prevented or suppressed by the sealing part 130.

On the other hand, the heat insulating portion 126 is not joined to any member that comes into contact, and the outer peripheral portion 126a and the bottom surface portion 126b of the heat insulating portion 126 are covered and supported by the sealing portion 130 from the opposite side of the combustion chamber 128. Yes. As a result, although the heat insulating portion 126 is not joined to any member in contact, the movement of the heat insulating portion 126 is restricted by the arrangement plate 122 or the sealing portion 130 so that there is no relative displacement from the sealing portion 130. Yes.

The sealing portion 132 is a flat plate member disposed on the opposite side of the heating plate 120 from the first radiation surface 120a. In the present embodiment, like the heating plate 120, the sealing portions 132 of the two combustion heaters 110 are integrally formed (see FIG. 2). And the sealing part 132 is fixed to the edge part of the extending direction (downward in FIG. 3A) of the outer wall part 120b of the heating plate 120 at a position away from the sealing part 130, and is a space between the sealing part 130 A heat insulating material 134 such as wool having heat insulating properties is sealed.

As described above, the main body container of the combustion heating system 100 is formed by closing the hole 126c of the heating plate 120 with the sealing portion 132, and the upper and lower wall surfaces (outer surfaces (outer surfaces of the outer wall portion 120b of the heating plate 120)) The area of the first radiation surface 120a of the heating plate 120 and the outer surface of the sealing portion 132) is larger. That is, the upper and lower wall surfaces occupy most of the outer surface of the main body container.

The first piping portion 136 is a piping through which fuel gas flows, and the second piping portion 138 is a piping through which exhaust gas flows. The second piping unit 138 is disposed inside the first piping unit 136. That is, the first piping part 136 and the second piping part 138 form a double pipe at the connection part with the combustion heater 110.

The arrangement plate 122, the heat insulating portion 126, the sealing portion 130, and the sealing portion 132 are provided with through holes 122d, 126d, 130d, and 132d penetrating in the thickness direction. The through holes 122d, 126d, 130d, and 132d have a positional relationship in which they overlap each other in the center portions in the surface direction of the arrangement plate 122, the heat insulating portion 126, the sealing portion 130, and the sealing portion 132. The first piping part 136 is inserted through the through holes 122d, 126d, 130d, and 132d. And the edge part of the 1st piping part 136 is fixed to the through-hole 122d of the mounting plate 122 in the position which makes the same surface as the surface at the side of the partition plate 124 of the arrangement | positioning board 122, and it is a sealing part among the 1st piping parts 136. A portion inserted through the through hole 130d of 130 is joined to the through hole 130d by welding or brazing.

Further, the partition plate 124 is provided with an exhaust hole 124b having a diameter smaller than that of the through hole 122d and penetrating in the thickness direction at a position overlapping the through hole 122d of the arrangement plate 122. The second piping part 138 is inserted into the exhaust hole 124b, and the end of the second piping part 138 is fixed to the exhaust hole 124b at a position that is flush with the surface on the first radiation surface 120a side of the partition plate 124. ing.

The end of the second piping part 138 protrudes to the first radiation surface 120a side from the end of the first piping part 136 and is separated from the heating plate 120, and the partition plate 124 is located on the center side in the surface direction. By being fixed to the end of the second piping part 138, the heating plate 120 and the arrangement plate 122 are separated from each other while maintaining a constant interval.

The introduction part 140 is formed by a gap between the arrangement plate 122 and the partition plate 124 and communicates with the first piping part 136. The fuel gas passes through the first piping part 136 and flows into the introduction part 140 from the through hole 122d of the arrangement plate 122. That is, the through hole 122 d of the arrangement plate 122 is an inflow hole through which the fuel gas flows into the introduction part 140. The introduction unit 140 guides the fuel gas flowing in from the through hole 122 d (inflow hole) of the arrangement plate 122 radially toward the combustion chamber 128.

Further, the flow path on the outlet side (combustion chamber 128 side) of the introduction part 140 is divided into a plurality of parts by a protruding part 124 c arranged on the outer peripheral end part of the partition plate 124.

FIG. 4 is a view for explaining the protrusion 124 c, and shows a perspective view of the combustion chamber 128 and a cross-sectional view of members surrounding the combustion chamber 128. Here, for easy understanding, the heating plate 120 is removed and the outline of the hidden portion of the partition plate 124 is indicated by a broken line.

As shown in FIG. 4, the protrusions 124c are provided at regular intervals in the circumferential direction of the partition plate 124, and a flow path 124d is formed between adjacent protrusions 124c. Thereby, the introducing | transducing part 140 and the combustion chamber 128 are connected by the flow path 124d by which the cross-sectional area of the communication part was narrowed. At this time, the interval between the adjacent projections 124c, that is, the width of the flow path 124d becomes the representative dimension of the cross section of the flow path. Here, the extinguishing distance d of the fuel gas is expressed by the size of the diameter of the tube wall model, and is obtained by the following mathematical formula 1.
d = 2λ · Nu ^1/2 / (Cp · ρu · Su) Equation 1

In Equation 1, λ is the thermal conductivity, Nu is the Nusselt number, Cp is the constant pressure specific heat, ρu is the density of the fuel gas, and Su is the combustion rate. Since the width of the flow path 124d is designed to be equal to or less than the extinguishing distance d, stable combustion is possible in the combustion chamber 128.

As shown in FIG. 3B, the fuel gas flowing into the combustion chamber 128 from the flow path 124d collides with the outer peripheral portion 126a in the combustion chamber 128 and temporarily stays there. The ignition device is provided in the combustion chamber 128 of one combustion heater 110 of the two combustion heaters 110. When the ignition device ignites the fuel gas introduced from the introduction unit 140, a fire transfer unit The fuel gas in the combustion chamber 128 in the other combustion heater 110 is also ignited via 102.

In this way, in the combustion chamber 128, the fuel gas flowing in from the inflow hole (the through hole 122d of the arrangement plate 122) burns. Combustion continues in both combustion chambers 128, and the exhaust gas generated by the combustion is guided to the derivation unit 142.

The lead-out part 142 is a flow path formed by a gap between the heating plate 120 and the partition plate 124 with the heating plate 120 and the partition plate 124 as side walls. The derivation unit 142 is continuous with the combustion chamber 128 and communicates with the second piping unit 138, and collects exhaust gas generated by combustion in the combustion chamber 128 from the combustion chamber 128 toward the center in the plane direction, From the exhaust hole 124b of 124, it guide | induces out of the combustion heater 110 via the 2nd piping part 138.

The heating plate 120 is heated from the back surface 120c of the first radiation surface 120a by the combustion heat in the combustion chamber 128 and the heat of the exhaust gas flowing through the combustion chamber 128 and the outlet portion 142. Then, the object to be fired is heated by the radiant heat from the first radiating surface 120a.

Further, since the partition plate 124 is formed of a material that is relatively easy to conduct heat, the exhaust gas flowing through the outlet portion 142 conducts heat to the fuel gas flowing through the introduction portion 140 via the partition plate 124 (see FIG. 3B). In particular, the exhaust gas flowing through the lead-out portion 142 and the fuel gas flowing through the introduction portion 140 form a counterflow with the partition plate 124 interposed therebetween, so that the fuel gas is efficiently preheated with the heat of the exhaust gas. And high thermal efficiency can be obtained.

Similarly, the exhaust gas flowing through the second piping section 138 flows through the first piping section 136 through the second piping section 138, transfers heat to the fuel gas in the counterflow, and preheats. By so-called excess enthalpy combustion, in which fuel gas is preheated in this way, combustion of fuel gas can be stabilized and the concentration of CO (carbon monoxide) generated by incomplete combustion can be suppressed to an extremely low concentration. .

Next, a continuous heating furnace 200 in which a plurality of the combustion heating systems 100 described above are arranged will be described.

FIG. 5 is a diagram for explaining the continuous heating furnace 200, and shows a schematic diagram of a cross section parallel to the conveying direction of the workpiece W in the continuous heating furnace 200 and in the vertical direction. As shown in FIG. 5, the continuous heating furnace 200 includes a transfer unit 210, a furnace body 212, a plurality of combustion heating systems 100 (heating units), and a plurality of cooling preheating units 214.

The transport unit 210 includes, for example, a transport belt 210a such as a belt, a roller 210b that stretches and supports the transport belt 210a, a motor mechanism 210c having a gear and a motor, and the transport belt 210a is driven by the power of the motor mechanism 210c. It rotates and conveys the to-be-baked object W in the direction of the white arrow in FIG. Although this to-be-baked object W is mounted on the conveyance part 210 in FIG. 5, you may be suspended by the suspension mechanism (not shown) provided in the conveyance part 210, for example. In addition, the transport band 210a may have a mesh structure or the like so as not to disturb the radiant heat transfer between the combustion heating system 100 or the cooling preheating unit 214 disposed vertically below and the workpiece W, for example.

The roller 210b supports a part of the transport band 210a from the vertically lower side in the furnace body 212. In addition, in order to suppress the curvature of the to-be-baked material W, when a conveyance belt | band | zone is comprised by a pair of net | network which pinches | interposes the top and bottom of the to-be-baked material W, it is good to provide the roller 210b on the outer side of a pair of net | network.

The furnace body 212 surrounds part or all of the transport band 210a and forms a firing space therein. Further, the combustion heating system 100 includes the first radiation surface 120a in the furnace body 212 with the first radiation surface 120a facing the conveyance band 210a in the furnace body 212 vertically above and vertically below the conveyance unit 210. Are arranged in parallel with the conveying direction of the workpiece W (hereinafter, abbreviated as “conveying direction”).
That is, the 1st radiation surface 120a heats the to-be-fired material W, when the to-be-fired material W opposes the to-be-fired material W conveyed by the conveyance part 210 without a shield.

In the furnace body 212, two cooling preheating sections 214 are provided in parallel with one combustion heating system 100 (combustion heater 110) on the downstream side (right side in FIG. 5) in the transport direction.

In addition, the cooling preheating unit 214 has a second radiation surface 214a that cools the object to be fired W. The second radiation surface 214a receives radiant heat from the to-be-fired object W when facing the to-be-fired object W conveyed by the conveying unit 210 without a shielding object.
As described above, the combustion heating system 100 and the cooling preheating unit 214 face the object to be fired W transported by the transporting part 210 without passing through the shield (the object to be fired W is the combustion heating system 100 or the cooling preheating). When the unit 214 is directly above or below the unit 214), heat exchange is performed with the object to be fired W. Therefore, the distance between the combustion heating system 100 and the cooling preheating unit 214 and the object to be fired W becomes the shortest during the heat exchange, and the heat exchange between the combustion heating system 100 and the cooling preheating part 214 and the object to be fired W is directly performed. And is done effectively.

Similar to the combustion heating system 100, the cooling preheating unit 214 is arranged with the second radiation surface 214a parallel to the transport direction while the second radiation surface 214a faces the transport band 210a in the furnace body 212. That is, the first radiating surface 120a of the combustion heating system 100 and the second radiating surface 214a of the cooling preheating unit 214 are arranged adjacent to each other in the conveying direction of the workpiece W, and the first radiating surface 120a and the second radiating surface are arranged. 214a is parallel.

In the continuous heating furnace 200, as described above, at least the combination of the combustion heating system 100 and the cooling preheating unit 214 is in the atmosphere in the furnace body 212 (in the firing space).

6A and 6B are diagrams for explaining the arrangement of the combustion heating system 100 and the cooling preheating unit 214. FIG. 6A shows a perspective view of the combustion heating system 100 and the cooling preheating unit 214, and FIG. FIG. 6A shows a cross section of the cooling preheating section 214 taken along line VI (b) -VI (b) in FIG. 6A. In FIG. 6A, in order to facilitate understanding of the connection relationship between the cooling preheating unit 214 and the first piping unit 136, a part of the second piping unit 138 is omitted and the flow of the fuel gas is indicated by a solid line arrow. It shows with.

As shown in FIG. 6A, the combustion heating system 100 has a width direction of the furnace body 212 (a direction perpendicular to the transport direction and horizontal, and indicated by a white double arrow in FIG. 6A. Is abbreviated as “width direction”) in a direction in which the combustion heater 110 is connected. In the furnace body 212, two combustion heating systems 100 are connected in the width direction. Therefore, four combustion heaters 110 are juxtaposed in the width direction.

Further, the length in the width direction of the cooling preheating unit 214 is approximately equal to the sum of the lengths in the width direction of the two combustion heating systems 100. As shown in FIG. 6B, a gas flow path 214b is formed inside the cooling preheating unit 214. As the fuel gas flows through the gas flow path 214b, the second radiation surface 214a is cooled and the fuel gas is preheated by the heat from the second radiation surface 214a.
Here, as shown in FIG. 6B, the cooling preheating unit 214 has a flat shape extending in the transport direction and the width direction. As a result, the preheating area of the gas passage 214b via the second radiation surface 214a can be made relatively wide, and the fuel gas in the gas passage 214b can be preheated effectively.

The supply pipe 216a is connected to the cooling preheating unit 214 and supplies fuel gas supplied from the outside to the gas flow path 214b. The end of the supply pipe 216a on the cooling preheating unit 214 side is arranged on either the one end 214c side in the width direction or the other end 214d side of the second radiation surface 214a. As a result, of the adjacent cooling preheating units 214, the cooling preheating unit 214 arranged in the downstream in the transport direction and the cooling preheating unit 214 arranged in the upstream in the end on the cooling preheating unit 214 side of the communication pipe 216b. The position of the part is reversed in the width direction.

The direction of the supply pipe 216a is not parallel to the second radiation surface 214a but perpendicular to it. That is, the supply pipe 216a is connected to the cooling preheating unit 214 perpendicular to the second radiation surface 214a. Therefore, the fuel gas that has flowed into the cooling preheating unit 214 from the supply pipe 216a collides with the back side of the second radiation surface 214a, and heat exchange between the fuel gas and the second radiation surface 214a is promoted.

The communication pipe 216b allows the first piping part 136 and the cooling preheating part 214 (gas flow path 214b) to communicate with each other. The position of the end of the communication pipe 216b on the cooling preheating section 214 side is opposite to the connection position of the supply pipe 216a in the width direction.

As described above, the cooling preheating section 214 (gas flow path 214b) communicates with the first piping section 136 of the combustion heating system 100 arranged in parallel in the transport direction via the communication pipe 216b. Specifically, the cooling preheating unit 214 communicates with a through hole 122 d (see FIG. 3A) provided in the arrangement plate 122 of the combustion heater 110 constituting the combustion heating system 100.

Further, one of the first piping parts 136 of the two combustion heating systems 100 arranged in the width direction communicates with the cooling preheating part 214 arranged in parallel downstream in the transport direction of the combustion heating system 100, and The other first piping part 136 communicates with the cooling preheating part 214 arranged in parallel upstream.

That is, the same number of cooling preheating units 214 as the combustion heating system 100 are provided in the furnace body 212, and the cooling preheating units 214 communicate with first piping units 136 connected to different combustion heating systems 100. .

As described above, the combustion heating system 100 and the cooling preheating unit 214 are alternately arranged in the transport direction, whereby the firing and cooling of the workpiece W to be transported are alternately repeated. Therefore, heat can be sufficiently transferred to the inside of the to-be-fired object W without overheating the surface of the to-be-fired object W. Further, the combustion heating system 100 and the cooling preheating unit 214 are disposed in the furnace body 212, and the cooling preheating unit 214 transfers the heat of the object to be fired W accompanying the cooling to the fuel gas. Heat loss is suppressed compared to a configuration in which the object to be fired W is air-cooled.
Further, by arranging the combustion heating system 100 and the cooling preheating unit 214 adjacent to each other in the conveyance direction, the arrangement of the combustion heating system 100 and the cooling preheating unit 214 becomes compact, and the total length of the continuous heating furnace 200 in the conveyance direction is increased. It can be shortened.

Moreover, in this embodiment, the to-be-baked object W is heated with the radiant heat from the 1st radiation surface 120a (combustion heating system 100), and is cooled by the radiation by the radiation to the 2nd radiation surface 214a (cooling preheating part 214). .

Here, as a comparative example, for example, a continuous heating furnace that heats and cools the object to be fired W by convection such as air or exhaust gas is assumed. In convection heat transfer, the surface of the object to be fired W comes into contact with a fluid (air, exhaust gas, or the like), so that the temperature difference between the surface temperature of the object to be fired W and the fluid immediately decreases. Then, the heat flux (heat transfer amount) proportional to the temperature difference is extremely lowered, and sufficient heat transfer to the inside of the object to be fired W is not performed. On the other hand, in the radiant heat transfer, since the object to be fired W and the radiation surface (the first radiation surface 120a and the second radiation surface 214a) are not in contact with each other and the temperature difference is difficult to be reduced, A heat flux proportional to the fourth power of the temperature is maintained relatively stably. Therefore, sufficient heat transfer to the inside of the workpiece W is possible.

Further, the heat flux of radiant heat transfer is hardly affected by the temperature of the atmosphere of the object to be fired W. Therefore, even if the air heated by the combustion heating system 100 affects the cooling preheating unit 214 side, the cooling performance of the object to be fired W is less likely to be lower than the comparative example described above. Furthermore, since the continuous heating furnace 200 has a heat transfer configuration that does not depend on the atmosphere of the object to be fired W, the object to be fired W can be heated and cooled even if the surroundings of the object to be fired W are vacuum. Yes.

FIG. 7 is a functional block diagram showing a schematic configuration of the continuous heating furnace 200. As shown in FIG. 7, the continuous heating furnace 200 includes an adjustment unit 218 in addition to the transfer unit 210, the combustion heating system 100, and the cooling preheating unit 214.

For example, the adjusting unit 218 is configured by a cover member having a lower emissivity than the second radiating surface 214a, and covers a part of the second radiating surface 214a, so that the second radiating surface is formed from the surface of the workpiece W. The amount of heat transfer by radiant heat to 214a is adjusted.

8A and 8B are diagrams for explaining the function of the adjusting unit 218, and both show changes in the heat flux to the workpiece W conveyed in the furnace body 212. FIG. FIG. 8A shows a case where the adjustment process by the adjustment unit 218 is performed, and FIG. 8B shows a case where the adjustment process by the adjustment unit 218 is not performed. 8A and 8B, the horizontal axis indicates time, and the vertical axis indicates heat flux and temperature. 8A and 8B, legend a indicates the heat flux to the object to be fired W, legend b indicates the surface temperature of the object to be fired W, and legend c indicates the center temperature of the object to be fired W.

As described above, for the workpiece W, heating by the combustion heating system 100 and cooling by the cooling preheating unit 214 are repeated alternately. In this way, the temperature (center temperature) inside the to-be-fired object W is raised while suppressing the rise in the surface temperature of the to-be-fired object W. As shown in FIGS. 8A and 8B, finally, the surface temperature and the center temperature of the object to be fired W are approximately constant.

8A and 8B, when the object W is heated, the surface temperature of the object W is higher than the center temperature of the object W, and from the surface of the object W to the inside. The heading heat flux has a positive value.

On the other hand, if the cooling performance by the cooling preheating unit 214 is too strong when the object to be fired W is cooled, the surface temperature of the object to be fired W is lower than the center temperature of the object to be fired W as shown in FIG. The heat flux from the surface of the fired product W toward the inside takes a negative value. This shows that it cooled so that it might radiate heat from the to-be-baked material W. As shown in FIG. In this case, in order to heat the amount of heat necessary for firing the object to be fired W, the amount of heat (heating time and output) by the combustion heating system 100 must be increased by the amount of heat released, resulting in heat loss.

In the present embodiment, the cooling performance by the cooling preheating unit 214 is appropriately suppressed by the adjusting unit 218, and as shown in FIG. The heat flux is maintained higher than the center temperature of the article W, and the heat flux from the surface of the article W to the inside takes a positive value. That is, no heat is radiated from the workpiece W.

As described above, the adjusting unit 218 transmits heat from the surface of the object to be fired W to the second radiation surface 214a by radiant heat so that the surface temperature of the object to be fired W is maintained at or above the center temperature of the object to be fired W. Adjust the amount of heat. This eliminates the need for heating to compensate for the heat radiation from the object to be fired W, and can suppress heat loss.

9A and 9B are diagrams for explaining a modification of the continuous heating furnace according to the present invention. FIG. 9A shows a first modification, and FIG. 9B shows a second modification. 9A and 9B, the outline of the cross section corresponding to FIG. 5 of the continuous heating furnaces 300 and 400 is shown by enlarging the upstream end in the transport direction.

A continuous heating furnace 300 shown in FIG. 9A includes a shielding unit 302 in addition to the same components as those of the continuous heating furnace 200 of the above-described embodiment. The shielding part 302 is located between the 1st radiation surface 120a of the baking heating system 100 and the 2nd radiation surface 214a of the cooling preheating part 214 in a conveyance direction. Furthermore, the shielding part 302 is also arranged on the upstream side of the first radiation surface 120a of the combustion heating system 100 arranged in the uppermost stream in the transport direction.

The shielding unit 302 has a surface 302a perpendicular to both the first radiation surface 120a and the second radiation surface 214a, and the first radiation surface 120a and the second radiation surface 214a are perpendicular to the transport direction. Rather than the object to be fired W (conveying band 210a in the furnace body 212).

The shielding portion 302 is disposed between the workpiece W and the second radiation surface 214a when the workpiece W is heated, that is, when the workpiece W is transported to a position facing the first radiation surface 120a. Shield. Therefore, heat loss due to radiation from the object to be fired W to the second radiation surface 214a is suppressed, and the object to be fired W can be efficiently heated. In addition, the shield 302 is disposed between the workpiece W and the first radiation surface 120a when the workpiece W is cooled, that is, when the workpiece W is transported to a position facing the second radiation surface 214a. Shield. Therefore, heat transfer due to radiation from the second radiation surface 214a to the workpiece W is suppressed, and an increase in the surface temperature of the workpiece W can be effectively suppressed. With this configuration, the heating and cooling of the object to be fired W are greatly increased, and sufficient heating up to the inside of the object to be fired W is possible.

The continuous heating furnace 400 shown in FIG. 9B includes the same components as the continuous heating furnace 200 described above. However, unlike the continuous heating furnace 200, only one combustion heating system 100 is arranged in the width direction, and the combustion heating system 100 and the cooling preheating unit 214 are arranged alternately two by two in the transport direction.

The first radiating surface 120a and the second radiating surface 214a that are adjacent to each other have the furnace body of the transport unit 210 at the ends 120d and 214e closer to each other than at the other ends 120e and 214f. It is inclined with respect to the transport direction so as to be close to the transport band 210a in 212.

That is, two adjacent combustion heating systems 100 are inclined in a direction in which the first radiation surfaces 120a are opposed to each other, rather than in a state where the first radiation surfaces 120a are parallel to each other. Similarly, two adjacent cooling preheating sections 214 are inclined in a direction in which the second radiation surfaces 214a are opposed to each other, rather than a state in which the second radiation surfaces 214a are parallel to each other.

As a result, when the object to be fired W is heated (when the object to be fired W is below the first radiation surface 120a), the second radiation surface 214a faces in a different direction from the object to be fired W. Heat loss due to radiation from W to the second radiation surface 214a is suppressed, and the object to be fired W can be efficiently heated. Further, when the object to be fired W is cooled (when the object to be fired W is below the second radiation surface 214a), the first radiation surface 120a faces in a different direction from the material to be fired W. Heat transfer due to radiation from 120a to the object to be fired W is suppressed, and an increase in the surface temperature of the object to be fired W can be effectively suppressed. With this configuration, the heating and cooling of the object to be fired W are greatly increased, and sufficient heating up to the inside of the object to be fired W is possible.

Moreover, the unit which consists of the combustion heating system 100 and the cooling preheating part 214 may be provided at intervals in a conveyance direction on the structure of a continuous heating furnace. In such a case, it is desirable to prevent heat radiation from the unit to the non-installed part of the unit in the continuous heating furnace as much as possible.
In the continuous heating furnace 500 shown in FIG. 10, the cooling preheating unit 214 is adjacent to the upstream side and the downstream side in the transport direction of the combustion heating system 100 to form a unit U that heats and cools the workpiece W. . Further, shielding units 502 are provided on the upstream side and the downstream side of each unit, respectively, and these shielding units 502 prevent heat radiation to the upstream side and downstream side of the unit U, in particular, radiation due to radiation. . Here, the specific configuration of each shielding unit 502 is the same as that of the shielding unit 302 shown in FIG. 9A.
In this continuous heating furnace 500, the unit U is surrounded by a shielding portion 502 to prevent heat radiation from the unit U, particularly heat radiation due to radiation, thereby improving heating efficiency in the unit U and preventing overcooling by the cooling preheating portion 214. I am trying.
That is, even when the unit U including the combustion heating system 100 and the cooling preheating unit 214 is provided at an interval in the transport direction, the unit U is not installed in the continuous heating furnace 500 (reference S in FIG. 10). The shielding portion 502 prevents heat radiation to the portion indicated by (2), particularly heat radiation due to radiation. As a result, effective heating and gradual cooling of the object to be fired W and effective preheating of the combustion gas in the cooling preheating unit 214 are possible.

In addition, the to-be-baked object by the continuous heating furnace of this embodiment is not specifically limited, For example, a foodstuff is mentioned. That is, you may use the continuous heating furnace of this embodiment for baking in the manufacturing process of foodstuffs, such as confectionery. For example, the continuous heating furnace of the present embodiment is used for the manufacture of baked confectionery. More specifically, for example, confectionery (thin confectionery, rice crackers and other cereals (rice etc.) as raw materials) In many cases, it can have a shape).

As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Is done.

For example, the combustion heater 110 is not limited to the configuration described above, and is supplied with air, city gas, and a mixed gas (premixed gas) of air and city gas, such as a radiant tube burner, a line burner, and an infrared ceramic burner. Other combustion heaters (heating units) may be used.

Further, in the embodiment and the modification described above, the case where the premixed gas flows as the fuel gas in the gas flow path 214b of the cooling preheating unit 214 has been described, but only air or only city gas flows. In the flow path from the gas flow path 214b to the combustion heating system 100, air and city gas may be mixed.

Further, in the above-described embodiment and modification, the combustion heating system 100 in which the two combustion heaters 110 are connected as the heating unit has been described as an example, but the combustion heater 110 is used alone as the heating unit. Alternatively, a combustion heating system in which three combustion heaters 110 are connected may be applied.

In the embodiment and the modification described above, the adjustment unit 218 is a cover member that covers the second radiation surface 214a. However, the adjustment unit 218 has a surface temperature of the object to be fired W that is to be fired. The cover member is not limited to the cover member as long as the heat transfer amount by the radiant heat from the surface of the object to be fired W to the second radiant surface 214a can be adjusted so as to be maintained at the central temperature of W or higher.

In the first modification described above, the first radiation surface 120a and the second radiation surface 214a are parallel to each other, and the shielding portion 302 is a surface perpendicular to both the first radiation surface 120a and the second radiation surface 214a. The case of having 302a has been described. However, the first radiation surface 120a and the second radiation surface 214a may not be parallel, and the shielding portion 302 is not parallel to at least one of the first radiation surface 120a and the second radiation surface 214a (perpendicular or It is only necessary to have an inclined surface. Such a modification can also be applied to the shielding unit 502 in the third modification.

In order to further enhance the effect of the shielding portions 302 and 502 in the first and third modified examples, the heat insulating properties of the shielding portions 302 and 502 (particularly on the side facing the combustion heating system 100) are increased, or radiation is performed. It is desirable to reduce the rate.
In order to improve the heat insulating properties of the shielding portions 302 and 502, use of a heat insulating board such as a steel plate panel, a vacuum panel, or ceramic sandwiched with a heat insulating material is conceivable. Further, in order to lower the radiation rate of the shielding portions 302 and 502, when using a glossy SUS plate or when used at a higher temperature (when oxidized with SUS), such as low radiation glass or platinum. A method of applying a metal coating is conceivable.

In the second modification described above, the two adjacent combustion heating systems 100 are inclined in the direction in which the first radiating surface 120a faces each other, and the two adjacent cooling preheating parts 214 face the second radiating surface 214a. The case where it inclines in direction was demonstrated. However, the first radiation surface 120a and the second radiation surface 214a may be bent so that the center side in the transport direction is recessed.

INDUSTRIAL APPLICABILITY The present invention can be used for a continuous heating furnace that heats an object to be fired by burning fuel.

W To-be-baked object 100 Combustion heating system (heating part)
120a First radiation surface 120d, 214e One end 120e, 214f Other end 200, 300, 400, 500 Continuous heating furnace 210 Conveying section 212 Furnace body 214 Cooling preheating section 214a Second radiation surface 214b Gas flow path 218 Adjustment section 302, 502 Shielding Part

Claims (6)

A furnace body;
In the furnace body, a transport unit that transports the object to be fired,
A plurality of first radiation surfaces that are heated by combustion and transfer radiant heat to the object to be fired that is transported by the transport unit, and are arranged in parallel in the furnace body in the transport direction of the object to be fired A heating unit;
A gas that preheats the gas used for combustion in the heating unit by heat from the second radiant surface that receives radiant heat from the baked material when facing the baked material that is being transported by the transport unit. A cooling preheating part having a flow path,
Two said cooling preheating parts are arranged side by side in the conveyance direction of the said to-be-baked thing, and these two are the continuous heating furnaces with which the flow direction of the gas in the said gas flow path was reversely set in the width direction .   The first radiation surface and the second radiation surface are arranged adjacent to each other in the conveyance direction of the object to be fired, and are positioned between the first radiation surface and the second radiation surface in the conveyance direction, Extends closer to the object to be fired than the first radiation surface and the second radiation surface in a direction perpendicular to the conveying direction, and is perpendicular to at least one of the first radiation surface and the second radiation surface, or The continuous heating furnace according to claim 1, further comprising a shielding portion having an inclined surface.   The first radiation surface and the second radiation surface are arranged adjacent to each other in the transport direction of the object to be fired, and the adjacent first radiation surface and the second radiation surface are both ends of the transport direction, The continuous heating furnace according to claim 1, wherein one end side closer to each other is inclined with respect to the transport direction so as to be closer to the transport unit than the other end side.   The first radiation surface and the second radiation surface are arranged adjacent to each other in the transport direction of the object to be fired, and the adjacent first radiation surface and the second radiation surface are both ends of the transport direction, The continuous heating furnace according to claim 2, wherein one end side closer to each other is inclined with respect to the transport direction so as to be closer to the transport unit than the other end side.   The apparatus further includes an adjustment unit that adjusts a heat transfer amount by radiant heat from the surface of the baking object to the second radiation surface so that a surface temperature of the baking object is maintained at a temperature equal to or higher than a center temperature of the baking object. The continuous heating furnace of any one of Claim 1 to 4 characterized by the above-mentioned. The continuous heating furnace according to any one of claims 1 to 5, wherein the cooling preheating unit is supplied with gas by a supply pipe oriented in a direction perpendicular to the second radiation surface.

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